The need for automotive occupancy sensor systems are set forth in detail in Corrado et al U.S. Pat. No. 5,482,314 which is incorporated by reference herein by way of background. Briefly, the incidents of injury by airbags to infants in rear facing child seats placed in the front passenger seat and to smaller occupants, such as young children and small or elderly adults is well documented. Proposed solutions include sensor systems that can discern the nature and location of occupants in passenger seats, or the absence of passengers, and in preselected scenarios signal the airbag deployment controller to not deploy the airbag. Alternately, airbags can be deployed partially, incrementally, or slowly, or a combination thereof; these are so-called "smart airbag" systems.
Critical to effective operations of such occupancy sensor systems are the suite of sensors. The sensors may be selected from one or more ultrasound (US), infrared (IR), capacitance, weight, inductance, visual (video) or other types of sensors. The sensors are very sensitive, must be tuned to the particular vehicle passenger compartment, and their output signals processed via algorithms for recognition of the nature and location of the occupant. Examples of such algorithms are set forth in the aforesaid Corrado et al U.S. Pat. No. 5,482,314 and copending application Ser. No. 08/731,355 filed Oct. 11, 1996 entitled Automotive Occupant Sensor System and Method of Operation By Sensor Fusion.
The sensors must be inexpensive, yet rugged, as vehicle operating conditions are varied and can be extreme. In addition, they need to be reasonably accessible for servicing or replacement. In addition, the sensor suite must be easy to mount during vehicle assembly, low cost, and reliable. Preferably, the sensors and related electronics should be grouped and provided as a subassembly by a specialty manufacturer.